Device for spherical turning

ABSTRACT

The device comprises a faceplate with a drive providing for rotation of the faceplate. In addition, the device comprises a support and a support feed mechanism. The support is made in the form of a lever of the secondclass at one end of which there is arranged a bearing made as a ball-and-socket joint and associated with the faceplate at a point located on the axis of rotation of the faceplate and on the other end of which there is located a tool holder mounting the rotary cup tool. The tool holder is equipped with means for controlling the degree of rotation of the cup holder in the process of turning the spherical surface. The spherical surface being turned, the faceplate and the support form a single closed dynamical system.

United States Patent [1 1 Ivanov et al.

[4 1 Aug. 7, 1973 DEVICE FOR SPHERICAL TURNING [76] Inventors: AlexandrPavlovich Ivanov, Nevsky prospekt, 139, kv. 76; Rudoll AlexeevlchRomanov, ulitsa Kuibysheva, 21, kv. 54, both of Leningrad, U.S.S.R.

[22] Filed: Feb. 24, 1972 [21] Appl. No.: 229,005

[52] U.S. Cl. 82/12, 82/1.5 [51] Int. Cl B23b 5/40 [58] Field of Search82/12, 11, 1.5

[56] References Cited UNITED STATES PATENTS 3,186,268 6/1965 Hoglund82/11 537,]26 4/1895 Schuckert et al 82/11 X FOREIGN PATENTS ORAPPLICATIONS 939,548 2/1956 Germany 82/12 37,930 10/1906 Switzerland82/12 Primary Examiner-Le0nidus Vluchos AttorneyEric H. Waters et al.

[57] ABSTRACT The device comprises a faceplate with a drive providingfor rotation of the faceplate.

In addition, the device comprises a support and a support feedmechanism. The support is made in the form of a lever of the secondclassat one end of which there is arranged a bearing made as aball-and-socket' joint and associated with the faceplate at a pointlocated on the axis of rotation of the faceplate and on the other end ofwhich there is located a tool holder mounting the rotary cup tool.

The tool holder is equipped with means for controlling the degree ofrotation of the cup holder-in the process of turning the sphericalsurface. The spherical surface being turned, the faceplate and thesupport form a single closed dynamical system.

5 Clalms, 4 Drawing Flgures PAIENILL Aw: H913 SHEET 1 [1F 2 DEVICE FORSPHERICAL TURNING The present invention relates to mechanicalengineering and, more particularly, the invention relates to devices forturning spherical surfaces.

Known in the art is a device for turning spherical surfaces in which apedestal mounted in the centre of the faceplate of a vertical lathecarries a support in the form of a lever of the second class the freeend of which is provided with a holder for a rotary cup tool. Thesupport is equipped with a feed mechanism (c.f. Technical Sheet No. 6,series 2, 1966 the central technical information bureau of the LeningradNational Economy Council, USSR).

The known device does not provide for accurategeometry spherical surface(with a deviation from a correct geometrical form of not higher than0.01 mm) necessary in various scientific and technical instruments andapparatus, for example in the bearings of the horizontal axle of a greatazimuthal telescope having a diameter of 2,200 mm or in large-sizerolling-friction bearings.

This stems from the fact that the known device has a disadvantage fromthe viewpoint of inevitable manufacturing errors determined by thesystem of tolerances and fits.

What is more, elimination of the axial play in the pedestal of thedevice is effected downwardly during the movement of the support fromits upper position to the horizontal position while elimination of thisplay during the movement of the support from the horizontal to thebottom position is effected upwardly.

Consequently, the centre of rotation of the support is not accuratelyfixed but floats within the space of the permissible play.

An object of the present invention is to eliminate the above-mentioneddisadvantages.

The specific object of the invention is to provide a simple device forturning spherical surfaces in which the errors of all its links arepractically compensated and allow this device to be used for precisionturning of spherical surfaces with a deviation from the corrctgeometrical form of not higher than 0.01 mm.

These and other objects are attained by providing a device for sphericalturning comprising a faceplate with a drive for its rotation, a supportmade as a lever of the second class and having at one its end a bearingcoupled to the faceplate at a point lying on the axis of rotation of thefaceplate and having at its other end a tool holder for mounting arotary cup tool, and a support feed mechanism; according to theinvention, this bearing is made in the form of a ball-and-socket jointand the tool holder is equipped with means for controlling the degree ofrotation of the tool in the process of turning the spherical surface, inwhich case the spherical surface faceplate and support form a singleclosed dynamical system.

The ball-and-socket joint is preferably composed of a ball rigidlyconnected to the faceplate and a socket member encompassing the ball andrigidly connected to the support so as to ensure uniform distribution offorces between all the points of contact with the ball.

The socket member of the joint may be made with a possibility of acontact with the ball along a circular surface. The socket member of theball-and-socket joint is preferably provided with three diamondprojections contacting the ball in three points disposed in the apicesof an equilateral triangle.

The means for controlling the degree of rotation of the cup tool ispreferably made as a drum rigidly secured to the tool, a rope having oneend secured on the cylindrical surface of the drum and passed through aguide roller mounted on the support and having the other end fixed in astationary clamp, in which case the place of mounting of the guideroller is to be determined depending on the conditions of a requiredangle of rotation of the cup tool during its one pass along the surfacebeing machined.

The proposed device provides for precision turning of spherical surfaceswith a high degree of accuracy of the geometrical form.

This device was employed for turning a radial block bearing with adiameter of its internal sphere of 2,200 mm for a large telescope. Inthis case the deviation of the surface from a correct geometrical formwas not in excess of 0.01 mm despite the fact that the radial and axialplay of the faceplate was within 0.2-0.3 mm.

The proposed device may be built around a typical metal cutting machine,for example a vertical lathe. In this case the faceplate of the verticallathe serves as a faceplate of the proposed device.

The invention will be-better understood from the following detaileddescription of some particular embodiments thereof, reference being madeto the accompanying drawings, in which:

FIG. 1 shows a device for turning internal spherical surfaces accordingto the invention;

FIG. 2 is a sectional view of the support taken in the line II-lI ofFIG. 1;

FIG. 3 is a view taken along the arrow A in FIG. 1;

FIG. 4 is a device for turning external spherical surfaces according tothe invention.

The device 1 for turning internal spherical surfaces has a faceplate 2(FIGS. 1, 2, 3) with a drive 3 for rotating the faceplate 2. The driveof the faceplate 2 may be accomplished as any known mechanism of thistype used in metal cutting machines providing for rotation of thefaceplate with a required speed necessary for predetermined turningconditions.

Installed on the faceplate coaxially therewith is a pedestal 4 which iskinematically connected to a support 6 through a ball-and-socket joint5.

The ball-and-socket joint 5 consists of a ball 7 with a tail (not shown)pressed into the pedestal 4 and a socket member 8 rigidly secured to thesupport 6. The ball 7 is made with a high accuracy and has a tolerancefrom an accurate geometrical form of not higher than 3 microns.

The socket member 8 consists of a split spherical bearing with a babbitlining scraped to the ball 7.

However, the socket member 8 of the ball-andsocket joint 5 may be madewith three diamond projections which contact the ball 7 in three pointsdisposed in apices of an equilateral triangle.

The support 6 mounted through its one end on the pedestal 4 by means ofthe ball-and-socket joint 7 has a tool holder 9 at its other end and iskinematically connected with a feed mechanism 10. This connection iseffected'through bronze blocks II which are fitted on a rod 12 pressedinto the support 6 between its ends. The blocks II are placed in theslots 13 of the holder 15 of the support 6. Springs 14 are also placedin the slots 13.

Thus, the support 6 consists of a lever of the second class one arm ofwhich is located between the pedestal 4 and the holder 15 of the support6 while the other arm of the lever is located between the pedestal 4 andthe tool holder 9.

The mechanism 10 for feeding the support 6 includes a drive l6, a link17 and the holder of the support 6.

The feed drive 16 may be of any known construction among those used formetal cutting machines and providing for feeding the support 6 with aspecified speed required for predetermined conditions of the process ofturning.

The tool holder 9 has a socket 18 for a cup tool 19 disposed relative tothe spherical surface 1 being turned so as to provide its self-rotationduring the process of cutting. (The direction of the self-rotation ofthe tool is shown by an arrow in FIG. 3).

The tool 19 is fitted on one end of the roller 20, a drum 2! beingfitted on the other end thereof.

Fixed to the drum 21 is a rope 22 laid along the support 6 to the roller23 mounted on the same and then passed to a stationary clamp 24.

Such mounting of the tool 19 ensures its limited selfrotation in whichthe tool makes only one revolution per its pass along the sphericalsurface being machined. The length of the cutting edge of the tool isselected so that each elementary portion of the cutting edge of the toolcorresponds to such an area of the machined surface at which there is noany appreciable wear of this elementary portion of the tool.

The limited self-rotation can be effected by fixing the end of the rope22 passing from the drum 21 in the point of intersection of arcs havingradii L and L +1, where L is the radius of the sphere being machined(or, more particularly, the length of the lever from the point of fixingthe tool 19 to the centre of the ball 7); l is the length of the arc ofthe single-turn drum 21, in which case the are L H is drawn from thepoint 25 of the beginning of the turning, while the are L is drawn fromthe end of the turning of the spherical surface.

The process of turning of a spherical surface 1 is effected as follows.Simultaneously with the rotation of the faceplate 2 the support 6 movesupwards under the action of the feed mechanism 10.

The tool 19, while moving from the point 5 to the point 25, performs theturning of the entire spherical surface.

in this case the tool 19 performs a single revolution per cycle ofturning the spherical surface 1 due the limited self-rotation of thetool provided by its mounting as described above.

FIG. 4 shown another modification of the proposed device intended forturning external spherical surfaces. In principle it does not differfrom the above-described device except for the shape of the support 27which is made as a L-shaped member.

We claim:

1. A device for turning spherical surfaces comprising in combination: afaceplate, a drive providing for rotation of said faceplate, a supportin the form of a lever of the secondclass, a mechanism for feeding saidsupport, abearing made in the form of a ball-and-socket joint disposedat one end of said support and connected to said faceplate at a pointlocated on the axis of rotation of said faceplate, a rotary cup tool, atool holder for said rotary cup tool disposed at the other end of saidsupport, means for controlling the degree of rotation of said cup toolin the process of turning said spherical surface, said holder mountingsaid tool, while said spherical surface, faceplate and support forming asingle closed dynamical system.

2. A device for turning spherical surfaces as claimed in claim 1, inwhich said ball-and-socket joint consists of a ball rigidly connectedwith said faceplate and a socket member encompassing said ball andrigidly connected with said support so as to provide for uniformdistribution of forces between all the points of contacts of said socketmember with said ball.

3. A device for turning spherical surfaces as claimed in claim 2, inwhich said socket member of said balland-socket joint contacts said ballalong a circular surface.

4. A device for turning spherical surfaces as claimed in claim 2, inwhich said socket member of the balland-socket joint is equipped withthree diamond supporting projections contacting said ball in threepoints disposed at apices of an equilateral triangle.

5. A device for turning spherical surfaces as claimed in claim 1, inwhich said means for controlling the degree of rotation of said cuptoolcomprises a drum rigidly connected to said tool, a rope one end of whichis secured on the cylindrical surface of said drum and passed through aguide roller mounted on said support, while the other end of the rope issecured in a stationary clamp, the place of. mounting of said guideroller being determined depending on the condition of provision of arequired angle of rotation of said cup tool per its pass along thespherical surface being machined.

I! I8 l i

1. A device for turning spherical surfaces comprising in combination: afaceplate, a drive providing for rotation of said faceplate, a supportin the form of a lever of the secondclass, a mechanism for feeding saidsupport, a bearing made in the form of a ball-and-socket joint disposedat one end of said support and connected to said faceplate at a pointlocated on the axis of rotation of said faceplate, a rotary cup tool, atool holder for said rotary cup tool disposed at the other end of saidsupport, means for controlling the degree of rotation of said cup toolin the process of turning said spherical surface, said holder mountingsaid tool, while said spherical surface, faceplate and support forming asingle closed dynamical system.
 2. A device for turning sphericalsurfaces as claimed in claim 1, in which said ball-and-socket jointconsists of a ball rigidly connected with said faceplate and a socketmember encompassing said ball and rigidly connected with said support soas to provide for uniform distribution of forces between all the pointsof contacts of said socket member with said ball.
 3. A device forturning spherical surfaces as claimed in claim 2, in which said socketmember of said ball-and-socket joint contacts said ball along a circularsurface.
 4. A device for turning spherical surfaces as claimed in claim2, in which said socket member of the ball-and-socket joint is equippedwith three diamond supporting projections contacting said ball in threepoints disposed at apices of an equilateral triangle.
 5. A device forturning spherical surfaces as claimed in claim 1, in which said meansfor controlling the degree of rotation of said cup tool comprises a drumrigidly connected to said tool, a rope one end of which is secured onthe cylindrical surface of said drum and passed through a guide rollermounted on said support, while the other end of the rope is secured in astationary clamp, the place of mounting of said guide roller beingdetermined depending on the condition of provision of a required angleof rotation of said cup tool per its pass along the spherical surfacebeing machined.